Garden Talk: December 15, 2011

From NGA Editors

Solar Eclipse

The next solar eclipse visible from the mainland U.S. won't happen until August 21, 2017. But if you're a gardener you won't have to wait that long. For horticultural, rather than astronomical excitement, plant the new heucherella cultivar 'Solar Eclipse'.

A 2012 offering from Terra Nova Nurseries, breeders of so many garden-worthy introductions of heucheras, tiarellas, and heucherellas, 'Solar Eclipse' displays leaves of reddish mahogany-brown accented with a border of bright lime green for a season-long addition of eye-catching color and pattern to shady garden beds.

Forming a compact, vigorous mound of foliage reaching 10-24 inches tall and about 18 inches wide, this hybrid, a cross between heuchera and tiarella or foamflower, produces sprays of small white flowers above the leaves in late spring. Great as a low edging, ground cover, accent plant, or in a container planting, 'Solar Eclipse' thrives in moist, well-drained soil and part shade and is hardy to zone 4.

Gardening for Stress Relief

You are never too old to reap the benefits of gardening. A new study had shown that cultivating plants is a great way for the elderly to relieve stress. And these anti-stress benefits are not simply the result of the physical exercise gardening provides.

Researchers in the United Kingdom surveyed 94 people between the ages of 50 and 88 [50-something editor's note: Whoa! Who's calling 50 elderly?] who either participated in an indoor exercise program or gardened. Both groups had similar levels of social support. They found that the gardening group reported significantly less stress than the exercising group.

The researchers speculated that these lower stress levels were the result of the ″contribution of engagement with nature and psychological restoration″ that gardening affords and pointed the way to using gardening as ″a health promoting behavior later in life.″

If you are a senior gardener who wants to keep gardening but is facing some physical challenges, or you want to help a senior stay active in the garden, try some of the suggestions for growing an accessible garden from Grace Young in her article for New Mobility magazine, Way to Grow: The Accessible Garden. For walking gardeners, she suggests using a Garden Kneeler bench to provide help rising from a kneeling position or to use as a bench. She points out that raised beds make it possible for gardeners seated in wheelchairs or scooters to cultivate the soil and suggests user-friendly tools for aging gardeners that are easy on backs, wrists, and hands.

To read an abstract of the research on stress relief, go to HortTechnology. To read the article on accessible gardening, go to: New Mobility.

Worried about Walnuts

Black walnuts (Juglans nigra) are stately forest trees that are found throughout the central and eastern parts of the U.S. from western Vermont in the east to northern Florida in the south, north to southern Michigan and eastern South Dakota and as far west as Oklahoma, Texas and Kansas. They are usually found scattered among other kinds of trees at the forest's edge rather than in large stands. Black walnut has long been valued for its timber, which is prized for furniture making, as well as its tasty nuts.

But Douglass Jacobs, professor of forestry and natural resources at Perdue University in Indiana is worried about walnuts. Along with his former doctoral student, Martin-Michel Gauthier, he has studied the physiology of these trees and is concerned about their ability to adapt to the warmer, drier summers and the increase in extreme weather events that climate change is likely to bring.

According to Jacobs, it is the droughts that are associated with climate change that will be most difficult for walnuts to weather. Noting that almost all climate change models predict drier conditions, he says, ″Changes in moisture could restrict its [the walnut's] ability to survive.″

Walnuts are also sensitive to damage from spring frosts and are one of the latest trees to leaf out in the spring. Erratic and unseasonable temperatures from the extreme weather events that are predicted to become more common could be another way that climate change affects the viability of walnuts.

Researchers at Purdue's Hardwood Tree Improvement and Regeneration Center are conducting a breeding program that is attempting to identify trees with genetic makeups that allow them adapt to different climatic conditions in the hope that this valuable hardwood tree isn't lost as the climate changes.

A Graveyard Mystery

Plants travel the world in a variety of ways. Some making the journey to a new location have the potential to spread invasively, creating big problems in their new homes.

That's why Charles Bryson, a botanist at the USDA's Agricultural Research Service Crop Production Systems Research Unit in Stoneville, Mississippi, always has an eye out for the appearance of new and potentially invasive plants. When graduate student Lucas Majure brought him an unknown sedge that he found growing in several cemeteries on the far side of the state in Meridian, Bryson took notice when the small, grass-like plant turned out to be blue sedge (Carex breviculmus), an Asian and Australian native that was previously unknown in North America.

Some sleuthing revealed that, with the exception of some campsites used by transients and vagrants, the sedge seemed to be only found in or around four cemeteries in Meridian. How did it get there?

It turns out that one of the cemeteries is Rose Hill Cemetery, the final resting spot for Emil Mitchell and Kelly Mitchell, reputed to be the King and Queen of the Gypsies in the United States. Their grave site has become a draw for visitors from around the world, who leave various offerings at the graves. Bryson speculates that seeds of the sedge trapped in a visitor's clothing may have been deposited at the grave site or were contained in the soil of plants left at the graves as gifts. Plants may have hitchhiked to the other cemeteries on workers' clothing or lawn care equipment.

For now, Bryson is keeping a close eye on the blue sedge, which is considered a weed in Asia. ″We could be looking at another headache for the lawn and turf world,″ he cautions. This botanical traveler may just have a gypsy's urge to wander further.